This invention relates to the polymerization of cyclic dihalophosphazenes oligomers to higher molecular weight substantially linear polydihalophosphazene polymers. The polymerization of cyclic dihalophosphazenes such as (NPCl.sub.2).sub.3 or (NPCl.sub.2).sub.4 to higher molecular weight linear polydihalophosphazene polymers is well known in the art.
Prior known processes for polymerizing such cyclic dihalophosphazenes involved the uncatalyzed or catalyzed thermal polymerization of such dihalophosphazenes either in a bulk process or in a solution process employing a solvent. Such processes are taught, for example, in U.S. Pat. No. 3,370,020 to Allcock et al., issued Feb. 20, 1968; U.S. Pat. No. 3,515,688 to Rose, issued June 2, 1970; U.S. Pat. No. 4,005,171 to Reynard et al., issued Jan. 25, 1977; U.S. Pat. No. 4,123,503 to Snyder et al., issued Oct. 31, 1978; U.S. Pat. No. 4,327,064 to Fieldhouse et al., issued Apr. 27, 1982; U.S. Pat. No. 3,917,802 to Allcock et al., issued Nov. 4, 1975; U.S. Pat. No. 4,137,330 to Prichard et al., issued Jan. 30, 1979; U.S. Pat. No. 4,242,316 to Sinclair, issued Dec. 30, 1980; PTO Patent Specification Publication No. 0004877, published May 12, 1982, to Snyder et al.; U.S. Pat. No. 4,225,567 to Halasa et al., issued Sept. 30, 1980; U.S. Pat. No. 3,937,790 to Allcock et al., issued Feb. 10, 1976; and U.S. Pat. No. 4,226,840 to Fieldhouse et al., issued Oct. 7, 1980.
The present invention concerns an improvement over all of the prior technology by use of a specifically defined supported coordination catalyst containing both titanium and aluminum. By this method lower temperatures and reaction times are possible and starting materials can be employed which are not ultra pure.